U.S. patent application number 10/150760 was filed with the patent office on 2002-12-26 for face masks for use in pressurized drug delivery systems.
Invention is credited to Smaldone, Gerald C..
Application Number | 20020195107 10/150760 |
Document ID | / |
Family ID | 23123345 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020195107 |
Kind Code |
A1 |
Smaldone, Gerald C. |
December 26, 2002 |
Face masks for use in pressurized drug delivery systems
Abstract
Face masks for use in pressurized drug delivery applications,
such as aerosol drug delivery systems, and a method of reducing
aerosol deposition in the region of the eyes are presented. The
face masks according to the various embodiments disclosed herein
contain features that reduce the inertia of the aerosolized drug in
perinasal areas. This results in a reduction in the amount of
aerosolized drug that is deposited in the region of the eyes by
inertial impaction, while at the same time, the features are
constructed to maintain the flow of the aerosolized drug into the
face mask so that the aerosolized drug is effectively delivered to
the respiratory system of the patient.
Inventors: |
Smaldone, Gerald C.;
(Setauket, NY) |
Correspondence
Address: |
DARBY & DARBY P.C.
P. O. BOX 5257
NEW YORK
NY
10150-5257
US
|
Family ID: |
23123345 |
Appl. No.: |
10/150760 |
Filed: |
May 17, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60292128 |
May 18, 2001 |
|
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Current U.S.
Class: |
128/205.25 ;
128/200.14; 128/203.12; 128/206.21 |
Current CPC
Class: |
A61M 16/06 20130101;
A61M 15/00 20130101 |
Class at
Publication: |
128/205.25 ;
128/206.21; 128/200.14; 128/203.12 |
International
Class: |
A61M 011/00; A62B
018/02; A61M 016/10 |
Claims
What is claimed is:
1. A face mask for use in a pressurized drug delivery system, the
face mask comprising: a body having a peripheral edge for placement
against a face of a patient and a nose bridge section formed in an
upper section of the body, the body having a pair of eye vents
formed therein, with one eye vent being formed on one side of the
nose bridge section and the other eye vent being formed the other
side of the nose bridge section, the eye vents for placement
underneath the eyes of the patient when the face mask is placed
against the face of the patient.
2. The face mask according to claim 1, wherein the face mask is
coupled to a nebulizer drug delivery system for delivering an
aerosolized drug through the face mask.
3. The face mask according to claim 1, wherein each of the pair of
vents comprises an eye cut out which is formed along the peripheral
edge of the face mask proximate to the nose bridge section.
4. The face mask according to claim 3, wherein the eye cut out has
a substantially semicircular shape.
5. The face mask according to claim 1, wherein each eye vent
comprises an eye cut out extending from the peripheral edge
inwardly into the mask body.
6. The face mask according to claim 5, wherein one end of each eye
cut defines an outer section of the nose bridge section.
7. The face mask according to claim 5, further including a
reinforcing member disposed along a section of the peripheral edge
that defines the eye cut out.
8. The face mask according to claim 7, wherein the reinforcing
member comprises a stiffener formed of a rigid material that is
attached to the mask body.
9. The face mask according to claim 7, wherein the reinforcing
member comprises a section of the mask that is formed of a material
that has a greater rigidity than mask material surrounding the
reinforcing member.
10. The face mask according to claim 9, wherein the reinforcing
member is formed of one of a reinforced plastic and a metal.
11. The face mask according to claim 1, further including a
supplemental vent.
12. The face mask according to claim 11, wherein the supplemental
vent comprises an opening formed in the mask body.
13. The face mask according to claim 12, wherein the opening is
formed in the mask body opposite the nose bridge section so as to
vent fluid from an inner cavity of the face mask in a direction
away from the nose bridge section.
14. The face mask according to claim 1, wherein each eye vent is
defined by an arcuate edge that comprises a section of the
peripheral edge of the mask body.
15. The face mask according to claim 1, wherein the eye vents
occupy greater than 10% of a total surface area of the face mask
body.
16. The face mask according to claim 1, wherein the eye vents
occupy less than 10% of a total surface area of the face mask
body.
17. The face mask according to claim 1, wherein the eye vents
occupy between about 2% and about 10% of a total surface area of
the face mask body.
18. The face mask according to claim 1, wherein the eye vents are
formed to have dimensions such that an inhaled mass of an
aerosolized drug supplied through the face mask is greater than 4%
of an initial amount of aerosolized drug that is present in the
drug delivery system and an amount of the aerosolized drug that is
deposited in a region of the eyes is less than 24% of an amount of
the aerosolized drug that is deposited on the face under a pattern
of breathing that is characterized as having a tidal volume of 50
ml, a frequency of breathing of 25 breaths per minute and a duty
cycle of 0.4.
19. A face mask for use in a drug delivery system that delivers an
aerosolized drug to a patient, the face mask comprising: a body
having a peripheral edge for placement against a face of the
patient and a nose bridge section formed in an upper section of the
body, the body having a pair of features formed therein on each
side of the nose bridge section along a peripheral edge of the
upper section of the body, the features being provided in perinasal
sections of the mask that are prone to leakage of the aerosolized
drug during administration of the aerosolized drug, wherein the
features are constructed to reduce the particle inertia of any
aerosolized drug that leaks through the perinasal sections and
thereby reduce deposition of the aerosolized drug in eye regions of
the patient.
20. The face mask of claim 19, wherein the pair of features
comprises first and second eye vents that are each formed by
cutting a section of the mask body along the peripheral edge in the
upper section of the mask body on one side of the nose bridge
section.
21. The face mask of claim 20, wherein each eye vent has a
substantially arcuate edge defined by the cut peripheral edge of
the body.
22. The face mask of claim 19, wherein the features are formed so
as to reduce the local velocity of aerosolized drug that is vented
in the perinasal sections around the nose bridge section by
permitting the aerosolized drug to pass over and around eyes of the
patient.
23. A method of reducing deposition of an aerosolized drug in eye
regions of a patient wearing a face mask, the method comprising the
step of: altering flow characteristics of the aerosolized drug as
it is vented in perinasal areas of the face mask during application
of the aerosolized drug.
24. The method of claim 23, wherein the step of altering the flow
characteristics comprises reducing the local velocity of the
aerosolized drug in the perinasal areas as the aerosolized drug is
vented.
25. A method of reducing deposition of an aerosolized drug in eye
regions of a patient wearing a face mask, the method comprising the
steps of: providing the face mask, the face mask having a body that
includes a peripheral edge for placement against the face and a
nose bridge section; and forming a pair of eye vents in the body
with one eye vent being formed on one side of the nose bridge
section and the other eye vent being formed on the other side of
the nose bridge section, the eye vents being formed in regions that
normally experience fluid leaks with the eye vents being formed
along the peripheral edge in sections that are for placement
underneath the eyes of the patient when the face mask is placed
against the face, the eye vents reducing deposition in the eye
regions by reducing the particle inertia of the aerosolized drug in
the eye regions.
26. The method of claim 25, wherein forming each eye vent comprises
the step of: cutting a section of the body along the peripheral
edge to form an eye cut out.
27. The method of claim 24, further including the step of: forming
a supplemental vent in the mask body.
28. The method of claim 27, wherein the supplemental vent comprises
an opening formed in mask body opposite the nose bridge section.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. patent
application Ser. No. 60/292,128, filed May 18, 2001, which is
hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a mask and more
particularly, to a face mask for use in delivering an aerosolized
drug or the like to a patient.
[0004] 2. Description of Related Art
[0005] Masks are commonly used in a wide range of applications and
have widespread use in a number of medical settings. For example,
masks are typically used in administering gases to a patient, e.g.,
an anesthetic agent, and more recently, masks have been
increasingly used in drug delivery systems, including nebulizer
drug delivery systems and metered dose inhalers using valved
holding chambers (MDI/VHC). Nebulization is the application of a
drug to a patient by means of an aerosol produced by a flow of gas.
The aerosol and the drug are breathed in through the mask and are
administered into the respiratory system of the patient as the
patient inhales. The MDI/VHC creates its aerosol from the expansion
of a volatile liquid into a gas within the VHC.
[0006] Nebulization is particularly used in the pediatric field as
a means for delivering a drug or the like. In patients, such as
young children, who have limited cooperation and attention span,
the delivery of an aerosolized drug is carried out primarily with
the use of a face mask. The face mask is placed over the nose and
mouth of the patient, held in place by a caregiver or by using
conventional straps or the like. The face mask is attached to an
aerosol drug delivery device. In the case of nebulizers, the face
mask is pressurized by the flow from the nebulizer and aerosol
fills the mask becoming available for inhalation via the nose or
the mouth. When the patient inhales, a negative pressure is applied
to the face mask reservoir and the aerosolized drug is inhaled and
enters into the respiratory system of the patient.
[0007] Metered dose inhalers are also used with face masks to
disperse a drug to a patient. These devices dispense a
predetermined amount of drug when activated and the patient is
required to inhale in order to draw the aerosolized drug into the
face mask reservoir and subsequently into the respiratory system of
the patient.
[0008] Nebulizer drug delivery is different from drug delivery
using a metered dose inhaler particularly in the degree of
pressurization of the face mask. Metered dose inhalers can
pressurize the mask to some degree, especially if aerosol is
sprayed directly into the mask and a spacer is not used. A spacer
is a device which is placed between the face mask and the source of
aerosol (typically a bottle). Often, the spacer has one way valves
and therefore is called a "valved holding chamber" (VHC). Face
masks are used for both nebulizer drug delivery and for metered
dose applications, but there are several associated
shortcomings.
[0009] Nebulizers readily pressurize the mask and deliver more drug
but leaks around the face are enhanced, resulting in increased
facial deposition of the drug. Thus, leakage around the mask
affects the performance of the particular device and in the case of
nebulizers, leakage actually enhances the delivery of the drug;
however, it is enhanced at the price of increased facial deposition
and potentially local side effects. In order to effectively
administer the aerosolized drug into the respiratory system of the
patient, the face mask should cover the entire mouth and nasal
openings of the patient.
[0010] The face mask is generally arranged so that it seats against
the cheeks of the patient and extends across an upper portion of
the bridge of the patient's nose. Because the bridge of the nose is
elevated relative to the rest of the patient's face, e.g., cheeks,
the upper portion of the face mask is slightly elevated relative to
surrounding portions of the face mask which extend across the
cheeks and under the mouth of the patient. This occurs even when
the patient attempts to produce a tight seal between the mask and
the face. For nebulizers, this produces certain leakage areas where
the aerosolized drug can be discharged underneath the face mask and
into the atmosphere. Because of the design of face masks and their
above-described placement over the face, leakage is universally
present in the perinasal areas on either side of the nose. This
results in a jet of leaked aerosol being oriented and deposited
directly into the eyes of the patient. In other words, aerosol is
discharged underneath the face mask in these perinasal areas and
flows directly towards the patient's eyes and unfortunately, many
of the conventional masks are constructed in such a manner that the
leaks that do occur are characterized as being high powered leaks
(high kinetic energy) due to the high velocity that the fluid has
as it flows underneath the mask and along the face directly into
the eyes.
[0011] This may lead to several undesired side effects. For
example, deposition of the leaked aerosolized drug may be
associated with direct trauma to the eyes and associated
structures. As leakage occurs, these organs are exposed to the
aerosolized drug. There is speculation that the risk of developing
cataracts increases as a result of aerosolized drugs being directly
deposited in the eyes of the patient. At the very least, leakage of
aerosolized drugs causes discomfort as the aerosol, traveling at a
great velocity, is discharged underneath the face mask and deposits
in the perinasal areas, including the eyes. In addition, leaks of
certain aerosols can cause dermatological problems in some patients
due to an adverse reaction between facial skin and the aerosol.
Other undesirable conditions may result from having the aerosolized
drug leaking and being deposited onto the face.
[0012] The disadvantages associated with conventional mask
constructions are readily apparent by viewing FIGS. 1, 1a and 2.
FIG. 1 is a front perspective view of a typical face mask 10 (that
is commercially available from Laerdal Medical Corporation of
Wappingers Falls, N.Y.). While, the face mask 10 is illustrated as
being worn by an adult in FIGS. 1 and 1a, it will be understood
that face mask 10 is designed to be worn by small children and
finds particular application in pediatric care where the patient is
unable or uncooperative in the administration of the drug. The face
mask 10 has a body 12 including a peripheral edge 14 which is
intended to engage a face of a patient. The body 12 defines a face
mask reservoir in which the patient's nasal openings and mouth are
in communication. The body 12 is typically made of a flexible
material, such as a thermoplastic, e.g., a PVC material. The body
12 has a central opening 16 defined in part by an annular
flange-like member 18 which extends outwardly from an outer surface
19 of the body 12. During use, the member 18 is coupled to other
components of a drug delivery system (not shown) to permit delivery
of the aerosolized drug. The opening 16 serves as a means for
delivering the aerosolized drug to the patient. Depending upon the
type of drug delivery assembly that is being used, e.g., a metered
dose inhaler or a nebulizer system, the opening 16 receives the
aerosolized drug as it is transported to the face mask reservoir
defined by the body 12. The breathing action of the patient causes
the aerosolized drug to be inhaled by the user and introduced into
the patient's respiratory system.
[0013] As previously mentioned, one of the deficiencies of the face
mask 10 is that leakage areas form around the peripheral edge 14.
More specifically, the peripheral edge 14 does not form a complete
seal with the face of the patient and accordingly, leakage flow
paths 17 with high local velocities are formed at certain areas
along the periphery of the face mask 10, especially in perinasal
areas 15. In fact, maneuvers to reduce leaks along edge 10 may
increase the velocity of leaks in perinasal areas 15. The perinasal
areas 15 are particularly prone to the formation of leaks and this
results in the aerosolized drug being discharged directly into the
eyes and the associated structures. As previously mentioned, there
are at least two different types of aerosolized drug delivery
systems that are commonly used with a face mask, such as face mask
10. One type utilizes a pressurized metered dose inhaler (MDI/VHC)
and the other type utilizes a jet nebulizer.
[0014] FIGS. 1 and 1a illustrate the face mask 10 as part of an
aerosol drug delivery system that utilizes a jet nebulizer 20. The
nebulizer 20 is operatively coupled to a compressor (not shown)
which generates compressor air through the nebulizer 20. The
nebulizer 20 has a body 30 which is coupled to a hose 31 that
connects to the compressor at a first section 32 and is constructed
so that compressor air flows therethrough. The drug to be delivered
is stored in the body 30 using conventional techniques. A second
section 34 of the nebulizer 20 communicates with the face mask
reservoir so that the aerosolized drug is delivered into the face
mask reservoir. The body 30 can include conventional venting and
filtering mechanisms.
[0015] During aerosol generation, compressor air flows through the
body 30 and into the face mask reservoir. This results in
pressurization of the face mask 10 and also facilitates leaks at
various locations (especially, the perinasal areas) around the face
mask 10 with enhanced facial deposition being realized. Once the
face mask 10 becomes fully pressurized, excess compressor air
(including the aerosolized drug) is vented through an exhaust vent.
This results in some of the aerosolized drug being lost into the
surrounding environment. The face mask 10 is partially
depressurized when the patient inhales but then as soon as the
patient stops inhaling and exhales, the face mask 10 is again fully
pressurized because of the continuous flow of the compressor
air.
[0016] When the face mask is placed on a patient, an imperfect seal
between the peripheral edge 14 of the face mask 10 and the
patient's face typically results due to a number of factors
(including face contour of the specific patient). This occurs for
small children, children, and adults. The leaks that occur due to
the pressurization of the face mask 10 result in the aerosolized
drug flowing according to flow paths indicated by arrows 17. These
leaks occur around the nose (perinasal areas), the cheeks and at
the chin of the patient. It has also been found that the degree of
pressure applied to the mask in an attempt to improve the seal
between the face mask and the face does not necessarily improve and
may in fact worsen the leakage of the aerosolized drug in the
perinasal areas when the patient inhales and draws the aerosolized
drug into the face mask reservoir. During therapy, local pressure
on standard masks may facilitate high local velocities that can
lead to eye deposition. For example a caregiver pressing on the
mask can seal leaks along the cheeks but promote leaks around the
eyes. The leakage of the aerosolized drug in the perinasal areas
results in the aerosolized drug being discharged towards the eyes
of the patient at high velocities due to the high kinetic energy of
the fluid. This is less than ideal as it may cause discomfort at
the very least and may also lead to other medical complications due
to the drug being discharged into the eyes of the patient.
[0017] Eye deposition is thus particularly a problem for those drug
delivery systems that exert greater pressure on the face mask
and/or maintain the face mask reservoir under pressure. Because
pressurization of the face mask 10 plays an important role in a
nebulizer drug delivery system and nebulizers have become an
increasingly popular means for delivering an aerosolized drug to a
patient in such a manner that exhibits a high degree of
pressurization in the face mask, the present applicant has studied
the amount of eye deposition which occurs when face mask 10 is used
in combination with the nebulizer 20 since the face mask
pressurization associated with nebulizer use promotes a higher
level of leakage around the eye region.
[0018] FIG. 2 is a gamma camera image obtained using a simulator
face as part of a radiolabel face deposition study carried out
using the face mask 10 of FIG. 1 in combination with the nebulizer
20. In these studies, the face mask 10 was attached to a breathing
emulator (not shown) which simulated the breathing pattern of a
particular type of patient. The breathing emulator includes a three
dimensional, contoured bench model face to which the face mask 10
was attached. A filter was placed in the mouth of the bench model
face so as to best determine the inhaled mass (actual quantity of
aerosol inhaled) as the filter represents the final path of the
particles passing into patient.
[0019] By using nebulized radiolabeled saline acting as a surrogate
drug in the nebulizer 20, the deposition pattern of the particles
can easily by determined. FIG. 2 represents deposition following
tidal breathing (also referred to as tidal volume) of 50 ml with a
minute ventilation of 1.25 liters/min, a pattern typical of a small
child. Airflow from the nebulizer 20 is 4.7 liters/minute and
therefore the face mask 10 is highly pressurized. Under these
conditions, aerosolized drug leaks from the mask at various points
on the face, as evidenced by the concentrated areas appearing in
the image. As seen in FIG. 2, there is a high level of deposition
in the area of the eyes of the patient and there is also a high
level of deposition in the chin and jaw areas of the patient. It
will be appreciated that other aerosol drug delivery systems which
cause the face mask to become pressurized will likely generate
similar data showing eye deposition of the aerosolized drug.
[0020] While face masks having been developed with venting
mechanisms to cope with the pressurization requirements of a
nebulizer or the like, these face masks still suffer from the
disadvantage that they have constructions that not only permit
aerosolized drug to be discharged in the perinasal areas but more
importantly, the aerosolized drug is discharged at high velocities
toward the eyes due to the imperfect interface between the face
mask and the face. In effect, this imperfect interface "funnels"
the aerosolized drug so that the aerosolized drug exits the face
mask at a high velocity toward the eyes.
[0021] What is needed in the art and has heretofore not been
available is a face mask which reduces the inertia of the
aerosolized drug in the perinasal areas thus reducing deposition in
the region of the eyes by inertial impaction, while maintaining
flow of the aerosol into the face mask so that the aerosolized drug
is effectively delivered to the respiratory system of the patient.
The exemplary face masks disclosed herein satisfy these and other
needs.
SUMMARY OF THE INVENTION
[0022] In one exemplary embodiment, a face mask for use in
pressurized drug delivery applications, such as aerosol drug
delivery systems, and a method of reducing aerosol deposition in
the region of the eyes are presented. The face masks according to
the various embodiments disclosed herein contain features that
reduce the inertia of the aerosolized drug in perinasal areas. This
results in a reduction in the amount of aerosolized drug that is
deposited in the region of the eyes by inertial impaction, while at
the same time, the features are constructed to maintain the flow of
the aerosolized drug into the face mask so that the aerosolized
drug is effectively delivered to the respiratory system of the
patient.
[0023] According to one exemplary embodiment, the face mask has a
body having a peripheral edge for placement against a face of a
patient. A nose bridge section is formed in an upper section of the
mask body to seat against the nose of the patient when the mask is
placed against the face during the application. The body has a pair
of eye vents formed therein, with one eye vent being formed on one
side of the nose bridge section and the other eye vent being formed
the other side of the nose bridge section. When the face mask is
worn by the patient, the eye vents are generally orientated
underneath the eyes of the patient. The eye vents are thus eye cut
outs formed along the peripheral edge of the mask body by removing
mask material. The present applicant has found that opening the
face mask at the sites of the greatest risk (i.e., the eyes), where
aerosolized drug flow is not desired, compels and ensures the local
reduction of particle inertia at the sites most at risk of facial
damage and irritation. The excisions in the face mask that serve as
eye vents thus minimize the local velocity and particle inertia
such that the particles do not impact on the surface of the face
and eyes and actually pass over the face and eyes without
deposition thereon. This results in a substantial reduction of
deposition in the region of the eyes compared to conventional face
masks.
[0024] The eye cut outs can be formed in any number of different
sizes and any number of different shapes (e.g., semicircular) based
upon the performance characteristics (i.e., inhaled mass value,
facial deposition amount, etc.) that are desired in the application
of the aerosolized drug. The eye vents can also be used in
combination with a supplemental vent that is also formed in the
face mask body. For example, the supplemental vent can be in the
form of an opening that is formed in the mask in a lower chin
section near the peripheral edge. By providing eye vents in the
face mask, a face mask is provided that substantially alleviates or
eliminates the discomfort and potential harmful consequences that
are associated with face masks that have leaks in the perinasal
areas which result in the aerosolized drug being "funneled" between
the peripheral edge of the face mask and the face and causing the
aerosolized drug to flow at great velocities into the eyes of the
patient.
[0025] Further aspects and features of the present invention can be
appreciated from the appended Figures and the accompanying written
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a front elevational view of a conventional face
mask shown as part of a nebulizer drug delivery system and in a
typical administering position on a patient such that it is
arranged so that the mask covers the nose and mouth of the
patient;
[0027] FIG. 1a is a side elevational view of the face mask of FIG.
1 with a section being cut-away to illustrate the flow paths of the
aerosolized drug when the face mask is worn by a patient;
[0028] FIG. 2 is an image obtained using a gamma camera scan of a
face model as part of a radiolabel face deposition study carried
out using the conventional face mask of FIG. 1 illustrating
particle deposition (aerosol drug) occurring in response to a
pediatric pattern of breathing (tidal volume 50 ml, frequency of
breathing 25 breaths per min, duty cycle 0.4);
[0029] FIG. 3 is a front perspective view of a face mask according
to a first exemplary embodiment shown as part of a nebulizer drug
delivery system and in a typical administering position on a
patient such that it is arranged so that the mask covers the nose
and mouth of the patient, wherein a portion of the face mask is cut
away to illustrate a vent formed therein;
[0030] FIG. 4 is a front perspective view of a face mask according
to a second exemplary embodiment shown as part of a nebulizer drug
delivery system and in a typical administering position on a
patient such that it is arranged so that the mask covers the nose
and mouth of the patient, wherein the face mask has a pair of eye
vents formed therein;
[0031] FIG. 5. is a front perspective view of a face mask according
to a third exemplary embodiment shown as part of a nebulizer drug
delivery system and in a typical administering position on a
patient such that it is arranged so that the mask covers the nose
and mouth of the patient, wherein the face mask has a pair of
reinforced eye vents formed therein;
[0032] FIG. 6 is a an image obtained using a gamma camera scan of
the face model as part of a radiolabel face deposition study
carried out using the conventional face mask of FIG. 5 illustrating
particle deposition (aerosol drug) occurring in response to a
pediatric pattern of breathing (tidal volume 50 ml, frequency of
breathing 25 breaths per min, duty cycle 0.4);
[0033] FIG. 7 is a front perspective view of a face mask according
to a fifth exemplary embodiment shown as part of a nebulizer drug
delivery system and in a typical administering position on a
patient such that it is arranged so that the mask covers the nose
and mouth of the patient, wherein the face mask has a pair of eye
vents formed therein and wherein a portion of the face mask is cut
away to illustrate a vent formed therein;
[0034] FIG. 8 is a an image obtained using a gamma camera scan of
the face model as part of a radiolabel face deposition study
carried out using the conventional face mask of FIG. 7 illustrating
particle deposition (aerosol drug) occurring in response to a
pediatric pattern of breathing (tidal volume 50 ml, frequency of
breathing 25 breaths per min, duty cycle 0.4);
[0035] FIG. 9 is a schematic diagram in the form of a bar graph
comparing drug delivery and facial deposition data obtained from
testing the conventional face mask of FIG. 1 and a set of the
exemplary face masks disclosed herein;
[0036] FIG. 10 is a table illustrating the mean deposition (of
inhaled mass, face including eyes, and the eyes only) as a percent
of the nebulizer charge when the conventional face mask of FIG. 1
and the face masks according to the present exemplary embodiments
are used;
[0037] FIG. 11 is a front perspective view of a face mask according
to a sixth exemplary embodiment shown as part of a nebulizer drug
delivery system and in a typical administering position on a
patient such that it is arranged so that the mask covers the nose
and mouth of the patient, wherein the face mask has a pair of eye
vents formed therein and wherein a portion of the face mask is cut
away to illustrate a vent formed therein;
[0038] FIG. 12 is a an image obtained using a gamma camera scan of
the face model as part of a radiolabel face deposition study
carried out using the conventional face mask of FIG. 11
illustrating particle deposition (aerosol drug) occurring in
response to a pediatric pattern of breathing (tidal volume 50 ml,
frequency of breathing 25 breaths per min, duty cycle 0.4);
[0039] FIG. 13 is a front perspective view of a face mask according
to a seventh exemplary embodiment shown as part of a nebulizer drug
delivery system and in a typical administering position on a
patient such that it is arranged so that the mask covers the nose
and mouth of the patient, wherein the face mask has a pair of eye
vents formed therein and wherein a portion of the face mask is cut
away to illustrate a vent formed therein;
[0040] FIG. 14 is a schematic diagram in the form of a bar graph
comparing drug delivery and facial deposition data obtained from
testing a set of the exemplary face masks disclosed herein; and
[0041] FIG. 15 is a table illustrating the mean deposition (of
inhaled mass, face including eyes, and the eyes only) as a percent
of the nebulizer charge when the face masks according to the
present exemplary embodiments are used.
DESCRIPTION OF A PREFERRED EMBODIMENT
[0042] FIG. 3 is a front perspective view of an exemplary face mask
100 according to a first embodiment. For purposes of illustrating
the benefits of the present invention, the face mask 100 is of a
similar construction as the face mask 10 with one exception, as
explained below. The face mask 100 thus includes a body 102
including a peripheral edge 104 which is intended to engage a face
of a patient. The body 102 defines a face mask reservoir in which
the patient's nasal openings and mouth are in communication. The
body 102 is typically made of a flexible material, such as a
thermoplastic, e.g., PVC material. The thickness of the material
and cross-section varies to allow different parts of the exemplary
face mask 100 to carry out their normal function. Thus, for
example, the face mask 100 is generally of a relatively thin
material with the peripheral sealing edge 104 also being of a thin
flexible construction so that it can flexibly engage the face of
the patient. The body 102 has a central opening 106 defined in part
by an annular flange-like member 108 which extends outwardly from
an outer surface 109 of the body 102.
[0043] The exemplary face mask 100 has a vent 110 formed in the
face mask 100 for decompressing the face mask 100 and also for
modifying the flow of the aerosolized drug that flows underneath
the face mask 100 (especially in the perinasal areas) during a
normal application when the face mask 10 is placed against the
face. The exemplary vent 110 is a generally circular shaped
opening; however, the shape of the vent 110 is not critical. The
vent 110 is formed in the face mask body 102 at the 6 o'clock
position. In other words, the vent 110 is generally formed in the
chin area of the face mask 100. The peripheral edge 104 extends
completely around the face mask 100 and therefore the vent 110 is
formed slightly away from the patient's face. This is desirable as
the vent 110 serves to discharge aerosol and therefore, it is
preferred to direct the aerosol downward and away from the
patient's face. The effect of forming the vent 110 is discussed in
greater detail hereinafter during the discussion of the data
presented in FIGS. 9 and 10. The dimensions of the vent 110 can be
varied depending upon a number of factors, including the precise
application, the size of the face mask, etc., so long as the vent
110 has sufficient dimensions that permit a desired amount of the
aerosolized drug to be inhaled by the patient, while at the same
time, the face and eye deposition is reduced. For example and
according to one exemplary embodiment, the face mask 100 has an
inner surface area of about 110 cm.sup.2 and the vent 110 is formed
so that the opening defined thereby has an area of approximately
3.1 cm.sup.2. It will be appreciated that the vent 110 can be
formed such that its dimensions are different than the above
example as the above example is merely illustrative and not
limiting. For example, the vent 110 can be formed to occupy an area
from about 2.0 cm.sup.2 to about 6.0 cm.sup.2 in another
embodiment.
[0044] While the vent 110 does serve to reduce aerosol deposition
in the facial areas and also serves to decompress the face mask
100, the Applicant realized that (1) even those face mask with
vents still have leaks between the face mask and the face
(especially the perinasal areas thereof) which permits aerosolized
drug to vent and (2) to increase the safety of face masks, it is
more desirable to control the flow characteristics of the
aerosolized drug that is discharged in the perinasal areas. Based
on this information, the Applicant constructed a face mask that
reduces face and eye deposition by modifying the flow
characteristics of the aerosolized drug in the perinasal areas.
[0045] Referring now to FIG. 4, an exemplary face mask 120
according to a second embodiment is illustrated. The exemplary face
mask 120 has a body 122 similar to the body 12 of the face mask 10
of FIG. 1 with the exception that the face mask 120 has a pair of
eye cut-outs or vents 130 formed by removing mask material along a
peripheral edge 124 of the body 122. The eye vents 130 are formed
on each side of a bridge section 126 of the face mask 120. The
bridge section 126 is the mask section that generally seats against
the bridge of the nose and interfaces with the cheeks of the
patient adjacent the nose. The illustrated eye vents 130 are formed
at the peripheral edge 124 and extend inwardly therefrom so as to
remove mask material along the peripheral edge 124 under the
patient's eyes. Each of the illustrated eye vents 130 has a
semicircular shape; however, the precise shape of the eye vents 130
is not critical. For example, the eye vents 130 can alternatively
be formed to have more of a rectangular shape in comparison to the
semicircular or angular eye vents 130 shown in FIG. 4.
[0046] The eye vents 130 vent aerosolized drug flow from the mask
into the region of the eyes. Contrary to one's initial inclination
of not providing vents directly in the area where aerosolized drug
flow is not desired, the Applicant has discovered that the
provision of eye vents 130 in the eye region actually greatly
improves the performance and the safety of the face mask 120 by
altering the flow characteristics of the aerosolized drug in the
eye region (i.e., the perinasal areas). One way of understanding
the advantages provided by the eye vents 130 is by investigating
the particle inertia of the fluid in the area of interest, namely
the region of the eyes. In general, the deposition of particles is
related to the diameters of the particles (hereinafter "a"), the
velocity of the particle movement imparted by the local flow
through the leak (hereinafter "U") in the face mask, and the local
geometry between the face mask and the face (hereinafter "D"). All
of these factors can be described together via local Stokes numbers
(hereinafter "Stk"). Stk is dimensionless term that is related to
particle inertia. The greater the inertia of particles, the greater
the tendency for these particles to impact the face (eyes) and
deposit on the face. Equation (1) sets forth the general
relationship between the various variables:
Stk.alpha.[a.sup.2(U)]/D (Equation 1)
[0047] where D can be related to U as set forth in Equation
(2):
U.alpha.Q/D (Equation 2)
[0048] where Q is the volume rate of flow out of the area of the
mask that exhibits leakage. It will be appreciated that increases
in local diameter of the site of the leak, decreases local linear
velocity. That is, the particle inertia is affected by the diameter
of the particles (a), the local velocity of the fluid (U) and has
an inversion relationship relative to the local diameters (D).
[0049] The exemplary face mask 120 reduces Stk by increasing D
which results in a decrease in U (Equation 2) and Stk. Further
effects on U occur via mask decompression as reducing pressure
within the mask further reduces Q. The latter accomplished via the
opening D, which acts as a vent.
[0050] The face mask 120 provides a face mask where aerosol flow
into the face mask is maintained (which is necessary for effective
drug delivery), while at the same time, the construction of the
face mask 120 reduces the deposition of aerosol in the region of
the eyes and the rest of the face by opening the face mask 120 in
the region of the eyes. Opening the face mask 120 at the sites of
the greatest risk and at the very locations where aerosolized drug
flow is not desired (the eyes) compels and ensures the local
reduction of particle inertia at the sites most at risk of facial
damage and irritation. Advantageously, the provision of eye vents
130 reduces particle velocity by increasing the space between the
mask (increased Stokes Diameter (D)) and further, by decompressing
the face mask reservoir (the area between the face and the inner
surface of the face mask 120 when it is worn), the pressure within
the face mask reservoir is reduced and this minimizes linear flow
to the eyes (i.e., variable (U) of Equation 2). It will be
understood that the local Stokes numbers are merely a tool to
describe the advantages of the present face masks and in no way
limit the scope of the present face masks as the principle can be
understood by other means.
[0051] The wide excisions in the face mask 120 that serve as the
eye vents 130 minimize the local velocity and particle inertia such
that the particles (i.e., the aerosolized drug) do not impact on
the surface of the face and eyes and actually pass over the face
and eyes without deposition thereon. Accordingly, the eye vents 130
are formed generally underneath the eyes (while leaving the bridge
section of the face mask in tact) in order to obviate the high
pressure effects that were previously observed at the peripheral
edge 124 of the face mask 120 due to the aerosolized drug escaping
in this region at high velocities. By forming eye vents 130 by
removing sections of the face mask 120, including peripheral edge
portions thereof, the interface between the peripheral edge 124 and
the face is eliminated in this region and therefore, aerosolized
drug is no longer "funneled" out of the mask 120 at the perinasal
areas at great velocities. Thus, low velocities in this region are
ensured independent of other multiple uncontrollable variables
(pressure of the mask on the face, nebulizer flow into the mask)
and deposition is always minimized.
[0052] Thus, the face mask 120 enhances the safety performance of
the face mask by reducing the velocity of the aerosolized drug as
it vents from the face mask 120 due to the face mask/face interface
being obviated in the eye region. In this embodiment, the eye vents
130 are of reduced dimensions compared to other embodiments. For
example, the face mask 120 has an inner surface area of about 110
cm.sup.2 and the eye vents 130 are formed so that they occupy an
area of about 5.5 cm.sup.2. However, these dimensions are merely
exemplary and it has been found that the eye vents 130 can have a
variety of dimensions since the present advantages are derived more
from the provision of the eye vents themselves in the face mask and
the location of the eye vents 130 in comparison to specific
dimensions of the eye vents 130.
[0053] FIG. 5 shows a face mask 140 according to a third
embodiment. The face mask 140 is very similar to the face mask 120
of FIG. 4 with the exception that the eye vents 150 have been
enlarged in comparison to the eye vents 130 of FIG. 4. For example,
the face mask 140 has an inner surface area of about 110 cm.sup.2
and the eye vents 150 occupy an area of about 10 cm.sup.2; however,
these dimensions are merely exemplary and not limiting since the
eye vents 150 can occupy an area less than 10 cm.sup.2 as well as
an area greater than 10 cm.sup.2. Once again, the eye vents 150 are
formed in the region of the eyes and the eye vents 150 can be
formed in any number of different shapes. The shapes of the eye
vents 150 in FIG. 5 are merely exemplary in nature. In this
particular embodiment using this particular type of face mask, the
eye vents can occupy From about 5 cm.sup.2 to about 11 cm.sup.2;
however, these dimensions can be varied outside of this exemplary
range. For this exemplary range, the eye vents occupy from about
4.5% to about 10% of the total surface area of the face mask.
[0054] Since the excision of more and more mask material to form
the eye vents 150 can serve to weaken the overall structural
rigidity of the face mask 140, the eye vents 150 can be formed such
that they each have a reinforcing member 160, which serves to
reinforce the structural rigidity of the face mask 140 and ensure
the robustness of the face mask 140. The reinforcing member 160 is
thus preferably formed around a peripheral edge 142 that defines
the eye vents 150 so as to increase the structural rigidity in the
region of the eye vents 150. This ensures that the eye vents 150
substantially maintain their shape and form when the face mask 140
is placed on the patient's head and pressure is applied to produce
some type of seal between the face mask 140 and the face.
[0055] The reinforcing member 160 can be any number of structures
that either can be integral to the face mask 140 itself or can be
later attached and secured to the face mask 140 after it has been
fabricated and the eye vents 150 have been formed. For example, the
reinforcing member 160 can be in the form of a reinforced rigid,
plastic piece that is securely attached to the face mask 140 using
conventional techniques, such as using an adhesive, bonding, etc.
By incorporating a rigid element into the face mask construction,
the region of the face mask 140 that includes the eye vents 150 is
less likely to deform or collapse but rather remains well defined
during use of the face mask 140. The reinforcing member 160 can
also be in the form of a metal bushing that is attached to the face
mask 140 using conventional techniques, such as those disclosed
above. Further, the reinforcing member 160 can be integrally formed
with the rest of the face mask 140 when the face mask 140 is
fabricated. For example, the reinforcing member 160 for each eye
vent 150 can be introduced into a mold and then the face mask 140
is formed therearound such that the reinforcing members 160 are
integral with the face mask 140. It will also be appreciated that
if the face mask 140 is formed using a molding process, two or more
different materials can be used to form the reinforced face mask
140 in that one material can be used to form the reinforced members
160 and another material can be used to form the rest of the face
mask 140.
[0056] FIG. 6 is a gamma camera image obtained using a stimulator
face as part of a radiolabel face deposition study carried out
using a face mask 140 of FIG. 5. As with the other studies, the
face mask 140 was attached to a breathing emulator (not shown) that
simulates the breathing pattern of a particular type of patient.
The visualized area represents the facial area and the eyes of the
patient. By using nebulized radiolabeled saline acting as a
surrogate drug in the nebulizer 20, the deposition pattern of the
particles can easily be determined. FIG. 6 represents deposition
following tidal breathing (tidal volume) of 50 ml with a minute
ventilation of 1.25 liters/min. This is representative of a
breathing pattern of a typical child. Airflow from the nebulizer 20
is 4.7 liters/minute and therefore, the face mask 140 is highly
pressurized. Aerosolized drug leaks from the mask at various points
on the face are evidenced by the concentrated areas appearing in
the image. The visualized area represents the facial area and the
eyes of the patient. In the study that yielded the results set
forth in FIGS. 9 and 10, the nebulizer 20 was a nebulizer
commercially available from PARI GmbH under the trade name Pari LC
Plus.
[0057] As seen in FIG. 6, the amount of facial deposition is
dramatically reduced compared to the image of FIG. 2, which
represents the facial deposition pattern of the same basic face
mask without eye vents 150. In other words, the aerosol deposition
is markedly reduced in the region of the eyes as well as the rest
of the face. The bar graph of FIG. 9 and Table 1 of FIG. 10
summarize the quantitative measurements of deposition on the face,
in the eyes and the drug delivery to the patient (inhaled mass). In
FIGS. 9 and 10, the conventional face mask 10 of FIG. 1 is
identified as "Laerdal", the face mask 100 of FIG. 3 is identified
as "M Laerdal", the face mask 120 of FIG. 4 is identified as
"Laerdal ShortEyeCut", and the face mask 140 of FIG. 5 is
identified as "Laerdal LargeEyeCut".
[0058] As the data of FIGS. 9 and 10 reflects, using the
conventional face mask 10 of FIG. 1 with nebulizer 20 resulted in
1.22% of the aerosolized drug initially placed in the nebulizer 20
being deposited in the region of the eyes of the patient (1.81% of
the aerosolized drug was deposited on the face). Thus, the amount
of the aerosolized drug that was deposited in the eyes as a
percentage of the amount deposited on the total face was 67%. In
other words, about 2/3 of the aerosolized drug that was deposited
on the face was deposited in the area of highest risk, namely the
eye regions. The inhaled mass (quantity of drug actually delivered
to the patient) for the face mask 10 was 5.76% of the amount placed
in the nebulizer 20.
[0059] When the face mask 100 of FIG. 3 was used, the inhaled mass
increased to 7.03%, while at the same time, the amount of
aerosolized drug being deposited in the region of the eyes
decreased substantially to 0.18% (0.53% deposited on the face).
Thus, only about 1/3 of the aerosolized drug that was deposited on
the face was deposited in the region of the eyes. However, this
data merely quantifies the results and does not characterize the
flow properties of the aerosolized drug that does escape underneath
the face mask and flows toward the eyes. In other words and as
previously mentioned, the safety benefits accorded by the face mask
are improved if not only less aerosolized drug is deposited in the
region of the eyes (and on the face for that matter) but also if
the flow characteristics of the escaping aerosolized drug are
modified in the region of the eyes. The provision of eye vents in
the face mask accomplishes these goals and enhances the overall
safety of the face mask.
[0060] When the face mask 130 of FIG. 4 was used, the inhaled mass
increased to 7.15%, while at the same time, the amount of
aerosolized drug being deposited in the region of the eyes
decreased substantially to 0.18% (0.57% deposited on the face).
Thus, only about 1/3 of the aerosolized drug that was deposited on
the face was deposited in the region of the eyes. When the face
mask 140 of FIG. 5 was used, the amount of aerosolized drug that
was deposited in the region of the eyes was about 0.10% with about
0.69% being deposited on the face. Thus, only about 14% of the
aerosolized drug that was deposited on the face was deposited in
the region of the eyes. This is a substantial improvement over the
face mask 10 of FIG. 1, in which about 67% of the aerosolized drug
that was deposited on the face was deposited in the region of the
eyes. More specifically, the modification of the face mask 140 by
forming eye vents 150 reduced eye deposition 92%. At the same time,
use of the face mask 140 resulted in 7.87% of the aerosolized drug
being inhaled (i.e., inhaled mass).
[0061] It will be appreciated that the provision of eye vents (of
varying dimensions) in the face mask not only maintains an
acceptable inhaled mass (and in most cases, results in an increase
in the inhaled mass) but more importantly, the eye vents serve to
modify the flow characteristics of the aerosolized drug (i.e.,
reduce the particle inertia of the aerosolized drug) in such a
manner that results in increased safety since the high local
velocities of the escaping aerosolized drug in the region of the
eyes that plagued conventional face mask constructions is
eliminated. In other words, the kinetic energy of the aerosolized
drug in the region of the eyes is reduced by controlling the
velocity of the aerosolized drug in the region of the eyes.
[0062] In the pediatric population, an inhaled mass value of about
4% is considered efficient for a drug delivery system. The low
percentages are inherent to drug delivery systems in pediatrics
because a large amount of the drug is wasted due to the drug either
being vented from the mask as well as being trapped in the
nebulizer or the like. The quantities deposited on the face and the
eyes are low on a percentage basis but quite high on a drug
delivery basis and thus it will be appreciated that facial and eye
deposition in such pressurized drug delivery systems is a matter
that deserves attention as it can lead to patient discomfort and
can potentially lead to more serious complications, especially with
the eyes.
[0063] Now referring to FIG. 7 in which a face mask 170 is
illustrated according to a fourth embodiment. Face mask 170 is a
combination of the face mask 100 of FIG. 3 and the face mask 140 of
FIG. 5 in that the face mask 170 includes not only the vent 110 but
also includes the eye vents 150. It will be appreciated that while
the exemplary vent 110 is located generally in the 6 o'clock
position, the location of the vent 110 is not limited to this
precise location and further, more than one vent can be formed in
the face mask 170 and used in combination with the pair of eye
vents 150. For example, a pair of vents (not shown) can be formed
in the lower cheek areas of the face mask 170, with one vent being
formed on one cheek and the other vent being formed on the other
cheek.
[0064] FIG. 8 is a gamma camera image obtained using a simulator
face as part of a radiolabel face deposition study carried out
using the face mask 170 of FIG. 7 in combination with the nebulizer
20. As seen in FIG. 8, the provision of vent 110 and eye vents 150
in combination results in a reduction of aerosolized drug
deposition in the region of the eyes (as well as the face). The
data contained in FIGS. 9 and 10 illustrate the benefits obtained
by incorporating vent 110 and eye vents 150 into the face mask 170.
More specifically, using the face mask 170 with the nebulizer 20,
resulted in 0.10% of the aerosolized drug being deposited in the
region of the eyes of the patient (0.60% on the face). At the same
time, the inhaled mass increased to 8.11%. Thus, one will
appreciate that while the vent 110 alone serves to reduce the
amount of facial and eye deposition, the provision of eye vents 150
enhances the safety of the face mask 170 by locally modifying the
flow characteristics (i.e., kinetic energy/local velocity) of the
aerosolized drug in the region of the eyes. This is a marked
improvement over the conventional face mask constructions that
suffered from having perinasal areas that permitted jets of high
velocity aerosolized drug to vent from underneath the face mask and
be directed into the eyes.
[0065] FIG. 11 illustrates a face mask 200 according to a fifth
embodiment. The face mask 200 is of a different type of
construction than the face mask 10 of FIG. 1; however, it is
intended for use in drug delivery systems, such as those which
employ a nebulizer. A face mask identical to or similar to the face
mask 200 is commercially available from Ferraris Medical Inc. of
Holland, N.Y. under the trade name Panda face masks. The face mask
200 has a body 202 that includes a peripheral edge 204 which is
intended to engage a face of the patient. The body 202 is typically
made of a flexible material, such as a thermoplastic, e.g., PVC
material. The body 202 defines a face mask reservoir in which the
patient's nasal openings and mouth are in communication. The body
202 has a central opening 206 defined in part by an annular
flange-like member 208 which extends outwardly from an outer
surface 209 of the body 202. As with the earlier face mask
constructions, the member 208 is coupled with a component (e.g.,
nebulizer 20) of the drug delivery system to permit delivery of the
aerosolized drug. The face mask 200 also preferably includes a vent
for releasing excessive pressure build-up and also can include one
or more other ports that receive one or more components of the drug
delivery system. For example, some types of nebulizers or the like
are intended to be connected to the face mask 170 at one or more of
these ports instead of at the main flange-like member 118. The face
mask 200 contains a bridge section 210 that is contoured to fit
around the patient's nose.
[0066] In this embodiment, the face mask 200 includes a vent 110
that is generally formed at the 6 o'clock position. While, the vent
110 is shown as being a circular opening, the vent 110 can be
formed to have any number of different shapes. The face mask 200
has an inner surface area of about 128 cm.sup.2 and the vent 110
comprises an opening having an area of about 3.1 cm.sup.2. Similar
to the embodiment shown in FIG. 4, the face mask 200 also includes
a pair of eye vents 220 formed on each side of the bridge section
210. The eye vents 220 are formed underneath the patient's eyes and
can be formed to have any number of different shapes. Thus, the
generally semicircular shape of the eye vents 220 is merely
exemplary in nature and the eye vents 220 can have more of a
rectangular shape according to another embodiment. The eye vents
220 function in the same manner as the eye vents described with
reference to earlier embodiments in that they minimize the local
velocity and particle inertia such that the particles do not impact
on the surface of the face and eyes but rather actually pass over
the face and eyes without deposition thereon. The eye vents 220
again serve to eliminate the interface between the face mask 200
and the face in the region of the eyes. According to one exemplary
embodiment, the eye vents 220 are openings that occupy an area of
about 3.4 cm.sup.2.
[0067] FIG. 12 is a gamma camera image obtained using a simulator
face as part of radiolabel face deposition study carried out using
the face mask 200 of FIG. 11 in combination with nebulizer 20. By
using nebulized radiolabeled saline acting as a surrogate drug in
the nebulizer, the deposition pattern of the particles is easily
determined. FIG. 12 represents deposition following tidal breathing
(tidal volume) of 50 ml with a minute ventilation of 1.25
liters/minute. Airflow from the nebulizer is 4.7 liters/minute and
therefore the face mask 200 is highly pressurized. As can be seen
from the image, the deposition of the aerosolized drug is not
concentrated around the region of the eyes but rather the
deposition is more spread out and less of the aerosolized drug is
deposited onto the face itself. The benefits of the construction of
face mask 200 will be further apparent in the discussion
hereinafter of FIGS. 14 and 15.
[0068] FIG. 13 illustrates a face mask 230 according to a sixth
embodiment. The face mask 230 is very similar to the face mask 200
of FIG. 11 in that it is of the same general construction and it
includes vent 110; however, the face mask 230 has larger eye vents
250 than the eye vents 220 of the face mask 200. The larger sized
eye vents 250 are similar to the eye vents 150 illustrated in FIG.
5 and can also be reinforced, if necessary. According to one
exemplary embodiment, the eye vents 250 comprise openings that
occupy an area of about 9 cm.sup.2. Each illustrated eye vent 250
has a semicircular shape; however, the shape of the eye vent 250
can vary. Accordingly, it will be appreciated that the area of eye
vents that are formed in the face mask 200, 230 can vary depending
upon a number of factors, including the acceptable robustness of
the face mask, what type of modification of the flow
characteristics is desired, etc. For example, the area that is
occupied by the eye vents can be in the range from about 3.0 cm to
about 10 cm.sup.2. For this exemplary range, the eye vents occupy
from about 2.3% to about 7.8% of the total surface area of the face
mask.
[0069] It will be appreciated that the face masks 200, 230 are
merely several examples of modifications to an existing face mask
construction which is intended for use with a drug delivery system,
such as a nebulizer drug delivery system, and there are a number of
alternative type face masks that can be used and modified by
forming eye vents therein either alone or in combination with one
or more vents, such as a vent at the 6 o'clock position. It will
therefore be understood that the face mask can be modified in the
same manner as the face mask of any of the earlier embodiments
(i.e., 6 o'clock vent alone, small eye vents alone, large eye vents
alone, or a combination of the 6 o'clock vent with either the small
or large eye vents).
[0070] The bar graph of FIG. 14 and Table 2 of FIG. 15 summarize
the quantitative measurements of deposition on the face, in the
eyes and the drug delivery to the patient (inhaled mass). In FIGS.
14 and 15, a conventional face mask similar to the face mask 200 of
FIG. 11 without vent 110 and vents 220 is identified as "Panda", a
face mask similar to face mask 200 of FIG. 11 with only vent 110 is
identified as "M Panda", a face mask similar to face mask 200 of
FIG. 11 with only eye vents 220 is identified as "Panda
ShortEyeCut", a face mask similar to face mask 240 of FIG. 13 with
only the eye vents 250 is identified as "Panda LargeEyeCut", the
face mask 200 of FIG. 11 is identified as "M Panda Short Eyecut",
and the face mask 240 of FIG. 13 is identified as "M Panda Large
Eyecut".
[0071] As the data of FIGS. 14 and 15 reflects, using a
conventional face mask with a nebulizer resulted in 0.468% of the
aerosolized drug initially placed in the nebulizer being deposited
in the region of the eyes of the patient (0.846% of the aerosolized
drug was deposited on the face). Thus, the amount of the
aerosolized drug that was deposited in the eyes as a percentage of
the amount deposited on the total face was 55.4%. In other words,
more than half of the aerosolized drug that was deposited on the
face was deposited in the area of highest risk, namely the eye
regions. The inhaled mass (quantity of drug actually delivered to
the patient) for the face mask was 4.499% of the amount placed in
the nebulizer.
[0072] When the face mask was modified by forming only vent 110
therein, the inhaled mass increased to 8.66%, while at the same
time, the amount of aerosolized drug being deposited in the region
of the eyes decreased substantially to 0.18% (0.63% deposited on
the face). Thus, only about 28.5% of the aerosolized drug that was
deposited on the face was deposited in the region of the eyes.
However, this data merely quantifies the results and does not
characterize the flow properties of the aerosolized drug that does
escape underneath the face mask and flows toward the eyes. In other
words and as previously mentioned, the safety benefits accorded by
the face mask are improved if not only less aerosolized drug is
deposited in the region of the eyes (and on the face for that
matter) but also if the flow characteristics of the escaping
aerosolized drug are modified in the region of the eyes. The
provision of eye vents in the face mask accomplishes these goals
and enhances the overall safety of the face mask.
[0073] When only eye vents 220 are formed in the face mask, the
inhaled mass increased to 8.85%, while at the same time, the amount
of aerosolized drug being deposited in the region of the eyes was
0.33% (0.97% deposited on the face). When only eye vents 250 are
formed in the face mask, the inhaled mass was 8.09% and the amount
of aerosolized drug being deposited in the region of the eyes was
0.18% (0.75 deposited on the face).
[0074] The data for face mask 200 (vent 110 plus eye vents 220)
reflects that the inhaled mass values is still within an acceptable
range (6.92%), while the amount of aerosolized drug being deposited
on the face was substantially reduced to 0.54% and further the
amount deposited in the region of the eyes was reduced to 0.13%.
This is a significant improvement over the standard face mask. When
the face mask 240 was tested, the inhaled mass was 7.84% and the
amount of aerosolized drug being deposited in the region of the
eyes was 0.14% (with 0.69% being deposited on the face)
[0075] One other advantage of the forming eye vents in a face mask
that is intended for use with a pressurized drug delivery system,
such as a nebulizer, is that existing face masks can easily be
retrofitted by simply forming the eye vents in the region of the
eyes using conventional techniques, such as a cutting process or
any other type of process that is capable of removing or excising
the face mask material along distinct lines to form the eye
vents.
[0076] The present applicant has recognized that certain drug
delivery systems, particularly nebulizer drug delivery systems,
enhance facial and eye exposure to aerosols. Nebulizer aerosol
delivery utilizing face masks pressurizes the face mask and
facilitates leaks at various points around the face mask with
enhanced facial deposition. Maneuvers that reduce this
pressurization reduce the leak and concomitant deposition. By
incorporating eye vents into the face mask, the shortcomings of
conventional face masks have been essentially eliminated. The eye
vents act to reduce particle inertia in the region of the eyes
Based on the data displayed on the images and quantified in Tables
1 and 2, the incorporation of eye vents can cause more than a 90%
reduction in the amount of aerosolized drug that was deposited in
the region of the eyes. It will be appreciated that the size and
cross-sectional shape of the eye vents may be altered and optimized
to minimize leak and maximize drug delivery. The size of the eye
vents should be tailored so that the inhaled mass value is within
acceptable ranges for the given application.
[0077] It will be understood that any of face masks disclosed
herein can be used in any number of applications where the face
mask is pressurized by a fluid to such a degree that pressurization
in the face mask results in leaks being formed around the face
mask. Preferably, the face mask is used in those applications where
it is desirable to preserve inhaled mass values. In other words,
the use of the face mask should allow a sufficient amount of the
aerosolized drug to flow into the face mask reservoir and then
subsequently into the respiratory system of the patient.
[0078] Eye vents can be incorporated into a vast number of medical
face masks that are intended for use in drug delivery systems or
the like. Furthermore, the use of any of the exemplary face masks
is not limited to only aerosol drug delivery systems. It will be
appreciated that the face mask can be used in other types of fluid
delivery systems having the same or similar characteristics as the
discussed aerosol drug delivery system, e.g., pressurization of the
mask and leakage, etc. While a number of the illustrations and the
experimental data are directed to use of the various face masks in
pediatric applications, it will be understood that the face masks
according to the present embodiments can be used in other
applications besides pediatric applications. For example, the face
masks can be worn by adults to administer an aerosolized drug,
etc.
[0079] The foregoing written description is of a preferred
embodiment and particular features of the present invention and is
not restrictive of the many applications or the breadth of the
present invention which is instead defined by the claims appended
hereto and substantial equivalents thereof.
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